Various types of electrochemical cells using metal as the fuel are known such as metal-air, Pb-acid, Ni—Cd and Ni—Zn batteries. For example, a metal-air cell typically comprises a fuel electrode at which metal fuel is oxidized and an air breathing cathode at which oxygen from ambient air is reduced during a discharge mode. During a charge mode, the metal fuel is reduced and electrodeposited at the fuel electrode, thereby storing the metal fuel for a future discharge process. A significant challenge with these types of cells is managing non-uniform deposits of metal fuel upon repeated charge/discharge cycling which can lead to electrode passivation, reduced charge capacities, poor cycling behavior, shorter cycle life and lower overall cell efficiency. The build-up of metal fuel (e.g. rough deposits, formation of dendrites) can cause problems including premature formation of electrical connections between electrodes and cell shorting. These problems are intensified after repeated partial cycling i.e. repeated cycles discharging to a low depth-of-discharge (DOD) directly followed by charging. The issues associated with partial cycling are well-known, for example in Ni—Cd batteries and is termed the “memory-effect.” Numerous successive cycles of partial discharging and charging produce small memory effects which can add up to a large memory effect. These effects can lead to errors in estimation of the state of charge (SOC) of the battery i.e. the amount of useable charge stored within the battery, as well as lead to non-uniform and rough deposits of metal on the fuel electrode during charging.
Among other things, the present application endeavors to provide an effective and improved way of operating electrochemical cells comprising electrodeposited metal fuel, minimizing non-uniformity and roughness of metal fuel deposits on cycling while enhancing cycle life and operating efficiency.